1. Field of the Invention
This invention relates in general to a method and apparatus for communicating emergency alert messages to members of the public. The invention provides an improved emergency alert system that allows for reliable transmission of emergency information to persons within a geographic area of concern.
2. Description of Related Art
Emergency alert systems are widely used. One common example of such a system is the emergency broadcast system used on television and radio. This system is often used to transmit information about potentially dangerous weather conditions. Other emergency alert systems rely on land-based telephone systems to send recorded messages to all persons within a particular area. Evacuation orders are another form of an emergency alert message, and these orders may rely on telephone systems, door-to-door communication by law enforcement officers, and other emergency communication methods.
As the public has become more concerned about terrorism threats and as communication systems have become more pervasive, a need has arisen for a better emergency alert system. Existing technologies suffer from many problems. A door-to-door communication of emergency information is effective at targeting only persons actually located in the area deemed to be at risk. Though door-to-door communication can be slow—the speed of this method depends on the number of persons to be contacted and the number of persons going door-to-door—it does provide the emergency information to the relevant members of the public. This benefit, however, comes at a very high price. Dedicating many law enforcement officers' time to going door-to-door costs a great deal of money and creates troublesome opportunity costs. If three-fourths of the local police force is going door-to-door to warn persons about an emergency situation, those officers cannot be patrolling for crimes or other problem situations. Though it is one means of geographically disseminating an emergency alert, door-to-door emergency communication is typically seen as a means of last resort.
Sirens also have been used to alert persons to emergencies. A siren system is perhaps most effective for a particular purpose. A chemical plant, for example, might use sirens to warn persons near the plant of a problem. Sirens have limited range and require regular upkeep. Sirens typically do not provide situation-specific information. Persons inside houses or in automobiles may not hear sirens even when they are relatively near the siren. The one upside to sirens is their partial geographic selectivity. Only persons within a certain radius of the siren will get the alert. Even this advantage is limited, however, because in most emergencies, the alert area will not be a perfect circle around a particular siren. For these reasons, sirens remain a generally poor means of alerting persons of an emergency.
The emergency broadcasting system (EBS) sends emergency alert messages via live television and radio feeds. Though this system can reach many persons quickly, its reach is both too broad and too narrow. It is too broad because an entire television and radio broadcast region will be covered when most emergency alerts are relevant to only some part of that region. It is too narrow because even persons who are using their televisions or stereos may not be receiving a live television or radio transmission. Television viewers may be watching a move on DVD, watching a pre-recorded television program, or viewing a satellite television broadcast. Persons listening to stereos may be listening to satellite radio or a music CD. None of these persons would receive the EBS alert.
Automated telephone calling systems are widely used for sending emergency alert messages. This system is geographically specific, because only those phones within a defined alert area will be called. There are, however, several problems with these systems. They are expensive to purchase and use. They do not reach nearly all the relevant public. Many persons miss phone calls, and most of these systems call only landline phones. That excludes all cell phones and VOIP phones. Because some numbers must be called many times to reach a person, this process also can be slow. Finally, when a telephone alert system is used, it can jam the local telephone switching network, thus slowing the system and making it very difficult for local persons to use their own phones.
Internet and e-mail also may be used to send emergency alert information. This process can work quickly, but it has limited reach. It is also not geographically limited.
Given the heightened concerns with emergency threats and the many flaws in existing emergency alert systems, there exists a need for a better system. Such a system should operate quickly and reach all persons within the appropriate geographic area. It should be affordable to own and operate. A cost-effective geographically targeted emergency alert system is needed.
Some geographic targeting has been attempted in the area of emergency alerts and other geographically targeted alerts. For example, the widely-used cellular telephone system has been used to provide a certain type of geographically targeted messaging. Cellular transmissions are relatively short-range transmissions, and therefore many cell towers are required throughout a geographic region to ensure continuous or nearly continuous coverage. When a particular cell tower transmits a message, that message will reach a limited geographic area.
If a cell tower transmits omni-directionally, the geographic area reached by the transmission will be generally circular. Those cell phone users with the right type of phone and who are located within the broadcast range of the transmitting tower will receive the message. More recently, technologies have been developed to allow cell towers to transmit somewhat directionally, which produces a pie or wedge-shaped coverage area.
Some cell systems also geographically target cell users based on the residence area of the user. This approach fixes a particular location or area for a user based on where the user lives or works. Other alert systems have used a similar approach in the past. For example, some tornado warning systems alert users based on a pre-determined, fixed location for the user. All systems of this type suffer from one major problem: they are used pre-determined, fixed location information for users who are highly mobile. These systems are not dynamic. They cannot account for movement of persons.
This reliance on fixed location data is a major drawback, because the system will miss in two important ways. First, this type of system will fail to alert visitors to the area of pending emergencies. A person who is visiting an area when a tornado strikes would not receive a warning with this type of system. Second, this type of alert system will warn residents who are not within the alert area. A person who resides in the warning area, but who is away at the time of the warning, will receive the alert. These two problems greatly reduce the efficacy of these types of warning systems.
The cellular tower location systems, using either omni-directional or semi-directional transmissions provide one means of resolving these problems. Only users who are physically within a geographic area will get the alerts. To achieve this result, however, the systems must limit the alert transmissions to rather crudely-defined geographic areas. Persons currently outside the broadcast area, but who are traveling toward the area, will receive no alert until within the broadcast area. Moreover, if the actual emergency is more localized than the cellular transmission area, this type of system will present the alert to persons outside the danger area.
Though the cellular transmission systems provide improvement over systems that rely on pre-determined, fixed user location data, the improvement is limited. To appreciate why, one must understand the two basic approaches to this problem. One approach is to consider the problem from the perspective of the alert transmission. This approach can be thought of as a “front-end” approach. The second approach is to consider the problem from the perspective of the users, the persons or businesses in a geographic area facing some risk. This approach can be thought of as a “back-end” approach.
All the systems described above are front-end systems. None of these systems rely on discrimination or decision at the user end. The geographic targeting all comes from the transmission end. The cellular tower systems are a good example. These systems are directional, but only in a front-end sense. All discrimination (i.e., all decisions concerning who gets an alert) is done at the front-end.
What is needed is a back-end solution to this problem, and one that allows for dynamic location fixes for users. An example of a crude back-end system would be one in which a message is broadcast to a large audience, and the members of the audience are to make their own determinations of whether the message is relevant to them. One simple example might be a PA announcement at a large sporting event (e.g., a football game) asking the person with the red convertible to move it from in front of the ticket office. The message of broadcasts to a large audience, and the members of that audience perform the discrimination steps of the process. Presumably, only the person (or persons) who parked a red convertible in front of the ticket office will respond to the message.
This general concept (i.e. back-end discrimination) has not been used in emergency alert systems. Perhaps this is because of a concern that widespread dissemination of targeted alert messages could induce hysteria. Or perhaps it is because those responsible for sending emergency messages tend to work at front-end facilities and have only considered the problem from that perspective. But whatever the reason for this focus, there has been a lack of attention on back-end type alert systems. There is, therefore, a real need for an improved, dynamic alert system that relies on back-end discrimination. Such a system would allow for relatively large area broadcasts of alert messages, potentially advising persons who are outside the alert area but approaching it. Such a system would also allow for precise area definition, or precise target audience definition (e.g., only firefighters or EMTs). It would not rely, however, on the individual user to perform the discrimination process (as in the football game example), but would use a technological solution. This new technology would perform the discrimination and then alert the user, if and only if the user is within the relevant geographic area and/or is within the relevant target audience.